目前大多数都在使用java集成 springboot进行开发，本文演示仅仅将 java换成 kotlin，其他不变的情况下进行开发。
一、安装支持插件
在 idea中安装 kotlin插件（大多数情况下会默认安装了）
二、maven配置 注意
kotlin目前不支持 lombok所以不能使用或引用 lombok相关的插件或依赖包，下面是一个排除示例，同时也不支持 maven-enforcer-plugin
<dependency>
<groupId>com.ayouran.common</groupId>
<artifactId>a-common</artifactId>
<version>1.0.0-SNAPSHOT</version>
<exclusions>
<exclusion>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclusion>
</exclusions>
</dependency>
maven的属性配置
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<kotlin.version>1.3.21</kotlin.version>
<!--增量编译-->
<kotlin.compiler.incremental>true</kotlin.compiler.incremental>
<!--关闭协程编译警告-->
<experimentalCoroutines>enable</experimentalCoroutines>
<spring-boot.version>2.2.4.RELEASE</spring-boot.version>
<spring-cloud.version>Hoxton.SR1</spring-cloud.version>
<swagger.version>2.7.0</swagger.version>
<main.class>com.lc.github.KotlinDemoApplication</main.class>
<querydsl.version>4.2.1</querydsl.version>
<mapstruct.version>1.3.1.Final</mapstruct.version>
</properties>
必要的依赖
<dependencies>
<!--反射支持包，不需要可以去掉-->
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-reflect</artifactId>
<version>${kotlin.version}</version>
</dependency>
<!--jdk8下的 kotlin支持包-->
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-stdlib-jdk8</artifactId>
<version>${kotlin.version}</version>
</dependency>
</dependencies>
编译部分
<build>
<plugins>
<plugin>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-maven-plugin</artifactId>
<configuration>
<correctErrorTypes>true</correctErrorTypes>
<languageVersion>${kotlin.language.version}</languageVersion>
</configuration>
<dependencies>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-maven-allopen</artifactId>
<version>${kotlin.version}</version>
</dependency>
</dependencies>
<executions>
<execution>
<id>kapt</id>
<goals>
<goal>kapt</goal>
</goals>
<configuration>
<correctErrorTypes>true</correctErrorTypes>
<sourceDirs>
<sourceDir>src/main/kotlin</sourceDir>
<sourceDir>src/main/java</sourceDir>
</sourceDirs>
<annotationProcessorPaths>
<annotationProcessorPath>
<groupId>com.google.dagger</groupId>
<artifactId>dagger-compiler</artifactId>
<version>2.9</version>
</annotationProcessorPath>
<annotationProcessorPath>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-apt</artifactId>
<version>${querydsl.version}</version>
<classifier>jpa</classifier>
</annotationProcessorPath>
<annotationProcessorPath>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct-processor</artifactId>
<version>${mapstruct.version}</version>
</annotationProcessorPath>
</annotationProcessorPaths>
</configuration>
</execution>
<execution>
<id>compile</id>
<goals>
<goal>compile</goal>
</goals>
<configuration>
<sourceDirs>
<sourceDir>src/main/kotlin</sourceDir>
<sourceDir>src/main/java</sourceDir>
</sourceDirs>
</configuration>
</execution>
<execution>
<id>test-kapt</id>
<goals>
<goal>test-kapt</goal>
</goals>
<configuration>
<sourceDirs>
<sourceDir>src/test/kotlin</sourceDir>
<sourceDir>src/test/java</sourceDir>
</sourceDirs>
<annotationProcessorPaths>
<annotationProcessorPath>
<groupId>com.google.dagger</groupId>
<artifactId>dagger-compiler</artifactId>
<version>2.9</version>
</annotationProcessorPath>
<annotationProcessorPath>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-apt</artifactId>
<version>${querydsl.version}</version>
<classifier>jpa</classifier>
</annotationProcessorPath>
<annotationProcessorPath>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct-processor</artifactId>
<version>${mapstruct.version}</version>
</annotationProcessorPath>
</annotationProcessorPaths>
</configuration>
</execution>
<execution>
<id>test-compile</id>
<goals>
<goal>test-compile</goal>
</goals>
<configuration>
<sourceDirs>
<sourceDir>src/test/kotlin</sourceDir>
<sourceDir>src/test/java</sourceDir>
<sourceDir>target/generated-sources/kapt/test</sourceDir>
</sourceDirs>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<proc>none</proc>
<source>${java.version}</source>
<target>${java.version}</target>
<annotationProcessorPaths>
<path>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
</path>
<path>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct-processor</artifactId>
<version>${mapstruct.version}</version>
</path>
</annotationProcessorPaths>
<compilerArgs>
<arg>-Amapstruct.suppressGeneratorTimestamp=true</arg>
<arg>-Amapstruct.defaultComponentModel=spring</arg>
</compilerArgs>
</configuration>
<executions>
<!-- Replacing default-compile as it is treated specially by maven -->
<execution>
<id>default-compile</id>
<phase>none</phase>
</execution>
<!-- Replacing default-testCompile as it is treated specially by maven -->
<execution>
<id>default-testCompile</id>
<phase>none</phase>
</execution>
<execution>
<id>java-compile</id>
<phase>compile</phase>
<goals>
<goal>compile</goal>
</goals>
</execution>
<execution>
<id>java-test-compile</id>
<phase>test-compile</phase>
<goals>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.6</version>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<archive>
<manifest>
<mainClass>${main.class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
有 java与 kotlin混合的情况，在上面的 <plugins>下加入下面的编译插件
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<proc>none</proc>
<source>${java.version}</source>
<target>${java.version}</target>
<annotationProcessorPaths>
<path>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct-processor</artifactId>
<version>${mapstruct.version}</version>
</path>
</annotationProcessorPaths>
<compilerArgs>
<arg>-Amapstruct.suppressGeneratorTimestamp=true</arg>
<arg>-Amapstruct.defaultComponentModel=spring</arg>
</compilerArgs>
</configuration>
<executions>
<!-- Replacing default-compile as it is treated specially by maven -->
<execution>
<id>default-compile</id>
<phase>none</phase>
</execution>
<!-- Replacing default-testCompile as it is treated specially by maven -->
<execution>
<id>default-testCompile</id>
<phase>none</phase>
</execution>
<execution>
<id>java-compile</id>
<phase>compile</phase>
<goals>
<goal>compile</goal>
</goals>
</execution>
<execution>
<id>java-test-compile</id>
<phase>test-compile</phase>
<goals>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
</plugin>
此 maven配置集成了 querydsl、mapstruct、dagger2的编译，基本上能满足常规的使用
三、创建入口函数类
四、编写入口函数
springboot的启动方法及 swagger的配置
@EnableAsync
@EnableSwagger2
@EnableScheduling
@SpringBootApplication
class KotlinDemoApplication : CommandLineRunner {
companion object {
@JvmStatic
fun main(args: Array<String>) {
SpringApplication.run(KotlinDemoApplication::class.java, *args)
}
}
@Bean
fun api(): Docket {
return Docket(DocumentationType.SWAGGER_2)
.ignoredParameterTypes(Session::class.java)
.select()
// .apis(RequestHandlerSelectors.any())
.apis(RequestHandlerSelectors.basePackage("com.ayouran.flow.controllers"))
.paths(PathSelectors.any())
.build()
.apiInfo(ApiInfoBuilder()
.description("ayouram-flow相关API")
.title("ayouram-flow")
.version("1.0")
.build())
.pathMapping("/")
}
override fun run(vararg args: String?) {
println("*************************** ok ***********************************")
}
}
五、创建数据库对象
import com.fasterxml.jackson.annotation.JsonFormat
import org.hibernate.annotations.DynamicInsert
import org.hibernate.annotations.DynamicUpdate
import java.util.*
import javax.persistence.*
/****
* 设备流量规则
*/
@Entity
@Table(name = "device_rules",
indexes = [Index(name = "device_no", columnList = "device_no"),
Index(name = "rules_no", columnList = "rules_no"),
Index(name = "deleted", columnList = "deleted")],
uniqueConstraints = [UniqueConstraint(name = "device_no_rules_no", columnNames = ["device_no", "rules_no"])])
@DynamicUpdate
@DynamicInsert
class DeviceRules {
@Id
@Column(name = "id", columnDefinition = "bigint(20) COMMENT 'ID,自增'")
@GeneratedValue(strategy = GenerationType.IDENTITY)
var id: Long? = null
@Column(name = "device_no", columnDefinition = "varchar(18) COMMENT '设备编号'")
var deviceNo: String? = null
@Column(name = "rules_no", columnDefinition = "varchar(18) COMMENT '规则编号'")
var rulesNo: String? = null
@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
@Column(name = "create_at", columnDefinition = "datetime COMMENT '创建时间'")
var createAt: Date? = null
@Column(name = "update_at", columnDefinition = "datetime COMMENT '修改时间'")
var updateAt: Date? = null
/**
* 触发jpa update代码需要执行的逻辑
*/
@PreUpdate
fun preUpdate() {
updateAt = Date()
}
/**
* 自动设置必要字段的值
*/
@PrePersist
fun prePersist() {
updateAt = Date()
createAt = updateAt
deleted = BaseEnum.NOT_REMOVE.index
}
}
注解使用了 hibernate的功能主要用于自动创建/更新表结构以及索引的生成，如果需要 mybatis版本的，只需要去掉这里面的注释就好。
六、创建仓库操作接口
基于 springboot-data-jpa的 repository
@Repository
interface DeviceRulesRepository : JpaRepository<DeviceRules, Long>,
JpaSpecificationExecutor<DeviceRules>, QuerydslPredicateExecutor<DeviceRules> {
fun getAllByDeviceNoAndDeleted(deviceNo: String, deleted: Int): Optional<MutableList<DeviceRules>>
}
七、创建一个业务接口来声明业务
interface DeviceService {
/**
* 查询设备的路由规则
*/
fun queryDeviceFlowRules(aPageRequest: APageRequest): PageResult<QueryDeviceFlowRulesVO>
}
八、创建一个业务接口实现来实现声明的业务
@Service
class DeviceServiceImpl @Autowired
constructor(private val deviceRepository: DeviceRepository,
private val deviceRulesRepository: DeviceRulesRepository,
private val querydslUtlis: QuerydslUtlis,
private val deviceMapstruct: DeviceMapstruct) : DeviceService {
private val logger = LoggerFactory.getLogger(javaClass)
override fun queryDeviceFlowRules(aPageRequest: APageRequest): PageResult<QueryDeviceFlowRulesVO> {
val qDeviceRules = QDeviceRules.deviceRules
val qFlowRules = QFlowRules.flowRules
var rredicate: Predicate? = null
if (StringUtils.isNotBlank(aPageRequest.query)) rredicate = qDeviceRules.deviceNo.eq(aPageRequest.query)
val exprs = arrayOf<Expression<*>>(qDeviceRules.deviceNo, qDeviceRules.deleted, qFlowRules.rulesNo, qFlowRules.flowMax,
qFlowRules.startTime, qFlowRules.endTime)
val results = querydslUtlis.getQueryFactory()
.select(*exprs)
.from(qDeviceRules)
.where(ExpressionUtils.allOf(rredicate))
.leftJoin(qFlowRules)
.on(qDeviceRules.rulesNo.eq(qFlowRules.rulesNo))
.orderBy(qDeviceRules.createAt.desc())
.offset((aPageRequest.pageIndex!! - 1) * aPageRequest.pageSize!!)
.limit(aPageRequest.pageSize!!)
.fetchResults()
return PageUtlis.retPage(results, querydslUtlis.getCollection(results.results, exprs, QueryDeviceFlowRulesVO::class.java) as Collection<QueryDeviceFlowRulesVO>)
}
}
这里使用了 querydsl来完成一个多表查询
九、创建一个 http服务接口
@RestWrapper
@RestController
@RequestMapping("/device")
@Api(value = "device", description = "设备相关接口", tags = ["device"])
class DeviceController @Autowired
constructor(private val deviceService: DeviceService) {
@GetMapping("/query_device")
fun queryDevice(aPageRequest: APageRequest) = deviceService.queryDevice(aPageRequest)
@GetMapping("/query_device_flow_rules")
fun queryDeviceFlowRules(aPageRequest: APageRequest) = deviceService.queryDeviceFlowRules(aPageRequest)
}
至此完成一个基本的开发过程，大多数情况下可以直接将 java代码粘贴到 kotlin文件中，会自动转换成合适的 kotlin代码(偶尔需要自己调整，毕竟编辑器不是万能的)
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原文链接：https://blog.csdn.net/u012599432/article/details/105455503